Current diesel engines operate at high temperatures under tight part tolerances that can present demanding thermal and mechanical conditions to the parts of the engine. For instance, large, smoldering soot particles can be ejected in the exhaust from the engines, which risk starting fires in forests, grasslands, etc. The thermal expansions associated with normal heating and cooling cycles of the engine cause gaps to appear between and among the various parts of the engine, such as the junction points between the exhaust manifold and the engine. This results in bypass of hot gases from the exhaust stream, thereby reducing engine efficiency, due to reduced turbo recovery efficiency, and increasing pollution, especially when a catalytic converter is employed. Moreover, the harsh mechanical conditions encountered in the diesel engines occasionally cause the breakage of parts, valve stems, keepers, and the like, which are ejected from the engine and into the exhaust system. If the parts are not captured, e.g., by a screen or parts catcher placed in the path of the exhaust gases, significant damage to the turbocharger can occur.
Conventionally, a diesel “turboscreen” consists of a metal plate provided with a plurality of perforations. The perforations can clog with soot, thereby increasing backpressure and reducing fuel efficiency. An example of a “debris separator” proposed for use in removing debris from the hot gas stream of engine exhaust is that of U.S. Pat. No. 4,076,508 (issued to Christensen). This system is primarily concerned with removing smaller debris that can pass through the perforations of conventional screens.
Specifically, a centrifugal separation system is proposed for swirling the hot gases radially outward into a chamber from which the gases then pass through a cylindrical screen. The debris is collected in a lower chamber and periodically removed from the assembly via an access port. In this system, the cylindrical screen is welded at one end “in cantilever fashion” to a flange, which is attached to the turbocharger inlet. Apparently, it is necessary to remove the entire housing in order to clean or replace the screen whenever it becomes plugged with soot.
Other approaches to cleaning the exhaust stream of diesel engines are focused on removing soot. For instance, U.S. Pat. No. 4,788,819 (issued to Henkel) employs an electrically charged cylindrical filter element that contains a loose material. The combination of loose material and electrical charge reportedly are effective in removing soot. However, this device is unconcerned with catching larger particles or parts and would likely entail significant maintenance requirements. Another particulate filter element is proposed by U.S. Pat. No. 5,298,046 (issued to Peisert). The filter element comprises a woven or nonwoven wire screen in the form of a spiral roll.
One object of the present invention is to reduce the time and labor associated with cleaning or replacing the debris screen provided between a diesel exhaust manifold and turbocharger. Another object of the present invention is to reduce the time and cost associated with maintenance of the exhaust manifold, generally.